1. Field of the Invention
The present invention relates generally to dust caps that are mounted upon fiber optic connector adapters and, more particularly, to translucent fiber optic adapter dust caps that allow the identification of light emanating from a fiber optic connector while the connector is capped or loaded into an adapter, while also providing protection against eye damage and dust contamination.
2. Technical Background
Fiber optic applications using optical connectors and adapters frequently include requirements for the identification of specific optical fibers during installation, interconnection and maintenance testing. Examples of such applications include local area networks, industrial networks and structured cabling systems, among others. Within these systems, connections between optical fibers are typically accomplished through the use of one or more patch panels. A patch panel typically includes a large number of optical connectors pre-installed into the backside of a number of connector adapters. The front side of the adapters are typically covered until needed using a dust cap operable for preventing dust from entering the adapter and contacting the polished end face of the back side connector. When a specific connector is needed for interconnection with a fiber optic jumper, a visible light source, commonly a red laser diode source from a Visual Fault Locator (VFL), is used to perform optical fiber tracing for connector identification.
With conventional connectors and adapters, it has been required that either the connectors must be removed from their respective adapters to allow for the visual identification of the visible light, or the adapter dust cap must be removed and the operator must peer into the adapter to view the visible light. In either case, the opportunity then exists for eye damage from the invisible light if a connector with infrared transmission laser power is viewed accidentally. Further, removing the connector from its respective adapter or removing the dust cap from the connector may also allow dust and contaminants to reach the polished end face of the ferrule, resulting in damage or signal degradation.
Conventional dust caps have typically been fabricated from opaque plastic materials, such as low-density polyethylene materials, due to the fact that they are primarily used for preventing contaminants from reaching the polished end face of the ferrule. Examples of such conventional opaque dust cap for use with ST and SC connectors are described in U.S. Pat. No. 6,227,717. Conventional dust caps have also been generally designed to be mounted directly upon a ferrule by inserting the front face of the ferrule through an open end of the dust cap, and have not been designed to be mounted to the connector adapter. Other conventional dust caps have been developed to allow for the identification of visible light without the removal of the dust cap from the ferrule, but do not allow for the identification of the visible light through the dust cap once the connector is loaded into an adapter, due to the fact that the dust cap must be removed from the ferrule prior to inserting the connector into the adapter. One example of such a translucent ferrule dust cap is described in U.S. Pat. No. 6,554,485 and includes a dust cap having a translucent end member that permits optical communication while the dust cap remains mounted upon a ferrule, thereby protecting the polished front face of the ferrule from contaminants. While these examples of conventional dust caps do prevent dust contamination and allow visible light identification in certain applications, by design they are not able to provide both protection against dust contamination and the ability to identify visible light emanating from the connector while the connector is loaded into an adapter. Exemplary applications in which connector loaded adapter identification may be useful include patch panels or outdoor stubbed fiber distribution hubs, among others.
Accordingly, what is desired is a translucent adapter dust cap that not only protects against dust contamination, but also allows for the viewing of light emanating from the connector while the connector is coupled to an adapter. Additionally, it would be desirable for the adapter dust cap to serve to diffuse a visible light source of sufficient power to cause eye damage if viewed along the optical axis (i.e., visible light from a visual fault locator). Further, it would be desirable for the adapter dust cap to serve to attenuate invisible infrared optical transmission power to prevent eye damage. Desirable translucent adapter dust caps may vary according to application and can be designed to accommodate various connector adapters, such as SC, LC, ST, and MU adapters, among others.